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Improving biosensing activity to carcinoembryonic antigen with orientated single domain antibodies.

Authors
  • Liu, Jinny L1
  • Raghu, Deepa2
  • Anderson, George P1
  • Goldman, Ellen R1
  • Christodoulides, Joseph A3
  • Raphael, Marc P3
  • 1 Center for Biomolecular Science & Engineering, Naval Research Laboratory, Washington, DC 20375, United States. , (United States)
  • 2 BioReliance, Sigma-Aldrich Corp, 14920 Broschart Road, Rockville, MD 20850, United States. , (United States)
  • 3 Materials Science and Technology Division, Naval Research Laboratory, Washington, DC 20375, United States. , (United States)
Type
Published Article
Journal
Heliyon
Publisher
Elsevier
Publication Date
Dec 01, 2017
Volume
3
Issue
12
Identifiers
DOI: 10.1016/j.heliyon.2017.e00478
PMID: 29423452
Source
Medline
Keywords
License
Unknown

Abstract

Carcinoembryonic antigen (CEA), also referred as CEACAM5, is integral to the adhesion process during cancer invasion and metastasis and is one of the most widely used tumor markers for assisting the diagnosis of cancer recurrence and cancer metastasis. Antibodies against CEA molecules have been developed for detection and diagnostic applications following tumor removal. Single domain antibodies (sdAbs) against CEA isolated from dromedary and llama exhibited high specificity in binding to tumor cells. However, because these CEA sdAbs were not designed to be orientated when conjugated to surface sensors, there is potential for significant improvements in their activity and limit of detection. Herein we modified the CEA sdAbs with two different C-terminal fusions designed to aid with orientation by way of the tail's charge and biotin binding. A fusion which incorporated the C-terminus addition of a positively charged tail (B5-GS3K) improved biosensor sensitivity to CEA while also retaining the sub-nanomolar binding affinity and thermal stability of the unmodified sdAb. Using our fabricated surfaces on bare gold chips and a multiplexed surface plasmon resonance imager (SPRi), we quantified the specific binding activities, defined as the percentage of bound epitopes to the total immobilized, of the sdAb fusions and anti-CEA mAb. Our results demonstrate that monovalent B5-GS3K exhibited significantly improved binding activity, approximately 3-fold higher than bivalent mAb.

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